rocks found for fish tank

Question
"hi i was out today at the lake dictrict i found some nice rock on my way down
off a hil the rock was dry i have put the rock in some water in a bowl i tested
the ph of the water and the rocks and it al seem fine will the rocks be ok with
my guppies tetras and mollies"


Answer
seems like it would be ok, just keep your eye on the ph level.  Granite is another great type of rock used for fishkeeping. Corals are rocks that can raise ph and be dangerous for most fish used to neutral ph ranges. River rocks and lake rocks are usually ok for tanks.